CLOUDS AND PRECIPITATION

By Nick Wesley

Adiabatic temperatures

Adiabatic- change in temperature without losing or gaining heat

Air expands as it cools Air compress as it warms

Orographic lifting

Happens when mountains stop air flow Air cools and makes clouds and rain On leeward side clouds lose

precipitation

Frontal wedging

Warm air and cold air meet Cool air goes under the warm air Are part of specific storm systems

convergence

Air in lower atmosphere flows causing lifting effects

Air flows up Creates strong solar heating

Localized convective lifting Produce rising thermals Warm plarcels go above condensation

level making clouds Thermal can be used for hang gliding

Stability

Stable air does not move vertically Stable air stays in place Unstable air rises

condensation

Air has to be saturated Condensation above ground is called

condensation nuclei Examples are dust, smoke, and salt

particles

Type of clouds

Cirrus clouds are high white and thin Cumulus are cloud masses Stratus clouds are layers that cover the

sky

High clouds

Three types cirrus cirrostratus, and cirrocumulus

Made of ice crystals May show storms coming

Middle clouds

Ranges 2000 to 6000 meters high Altocumulus clouds are large and dense Light snow or drizzle may occur

Low clouds

Three types are stratus, stratocumulus, and nimbostratus

The clouds form in layers Nimbostratus clouds form in stable air

Clouds of vertical development

Base is in low heights Expands up to middle or high altitudes Are associated with unstable air

Fog

Appearance and structure are the same as clouds

Forms in warm and cooled moist places Cool air + warm air = condensation

Cold cloud precipitation

Bergeron process relies on supercooling and surpersaturation

Liquid water below 0 degrees Celsius is supercooled

Snow flakes are formed by this process

Warm cloud precipitation

Collision-coalescence process forms rain

Salt can remove water vapor from the air

Rain can be found in clouds below freezing level

Rain and snow

Temperature surface above 4 degrees Celsius will melt snow and turn into rain

Temperatures warmer then -5 degree Celsius will have ice crystal join and make snow

These snow flakes are heavy and have high moisture contents

Sleet, Glaze, and hail

Sleet forms when air temperature meets subfreezing temperatures

Hail comes from cumulonimbus clouds Ice pellets are carried by updraft through

cloud layer and adds more ice